George Zimmerman, the 29-year-old neighborhood watch commander, fatally shot 17-year-old Trayvon Martin but was acquitted by a jury that apparently concluded he was in fear for his life. Marissa Alexander, a 32-year-old mother of three, fired what she described as a warning shot in the direction of her husband — against whom she had a protective order — and two stepsons. No one was injured, but she was convicted of attempted murder and sentenced to 20 years.

In the wake of the Zimmerman trial and the national debate on race and justice that it unleashed, Alexander’s case — from 2010 — has drawn renewed attention, including an online petition seeking a pardon from Gov. Rick Scott.

Supporters say Alexander, who is African-American, was a victim of ingrained racism in Florida’s courts. Some claim that those same alleged prejudices allowed Zimmerman, who has a white father and a Peruvian mother, to walk free after killing Martin, who was black.

But Angela Corey, the state attorney who prosecuted Alexander and also oversaw the Zimmerman case, says there were “zero parallels.” The facts surrounding Alexander’s conviction, she adds, are more complex than the Twitter-fueled pardon campaign makes it appear.

“I think social media is going to be the destruction of this country,” Corey said. “How dare people just repeat something without checking it’s true.”

Alexander was convicted of three counts of aggravated assault with a deadly weapon for firing a gun into a wall close to where her husband, Rico Gray, and stepsons were standing, after she and Gray had a dispute.

When questioned by police, Alexander said she discharged the weapon to avoid being beaten by Gray, who was subject to an injunction prohibiting violent contact with her. Alexander, who had given birth to Gray’s child nine days earlier, said she had no intention of killing him.

A judge rejected her bid to mount a defense under Florida’s controversial “stand your ground” law, which allows people to use deadly force if they or their homes are in danger. After she rejected a three-year plea deal, Alexander was convicted and sentenced to 20 years, as required by Florida’s strict sentencing guidelines on crimes involving a gun.

Kevin Cobbin, Alexander’s lawyer, said his client was justified in firing her gun because Gray “had put his hands on her and there was a fight in the bathroom.”

“The judge decided not to make the call to grant ‘stand your ground,’ ” Cobbin said. “If it had been a white female, I believe she would have,” Cobbin said.

Florida Democratic Rep. Corrine Brown, whose district includes parts of Jacksonville, last year described Alexander’s case as evidence of “institutional racism.”

However, Corey said that there are other, less widely shared details that paint a different picture.

She said Gray’s sons were pulling on their shoes to leave the house when Alexander raised her weapon to fire — in other words, they and their father were about to leave.

“She put a round in the chamber, and she fired that shot out of anger, not fear,” Corey said. “She didn’t need to use that gun. Those kids were scared to death. They ran for their lives.”